There exist many pumps, pumping devices, supplying and conducting devices, fluid-transporting devices and the like. Included among them are vane pumps, eccentric vane pumps and sliding vane pumps as well as rotary vane pumps and other pumps having eccentrically moved elements. Many pumps are developed for special applications. Many of these pumps compress the conveying medium for the purpose of transporting. Constituents of the medium to be conveyed and pumped can suffer, especially when conveying foodstuffs and other sensitive goods. Many pumps also produce a discontinuous or pulsating conveying flow. Gentle conveying is important, especially for sensitive goods. In many pumps, such as gear pumps or the like, residual quantities remain in part regions of the transporting elements when the sealing is applied. Surges of high intensity are frequently produced as a result. The pumps therefore have to operate correspondingly slowly or be equipped with additional discharge openings and discharge channels.
The rotary piston machine with fixed abutments and oscillating piston vanes in accordance with DE 648 719 has oscillating piston vanes which are mounted in the outer hollow cylinder. This solution is not comparable with sliding vanes.
The rotary piston pump or the rotary piston motor with external rotor in accordance with DE 37 24 077 has roller-shaped sealing elements in the external housing, and these perform rotary oscillations about their axis and seal in sliding manner by means of an edge on the cylindrical stator. Radially moving sliding vanes which are pushed in and out in accordance with eccentricity are not provided.
Details regarding the supply and discharge of the medium are not discussed. The same applies to the associated documents DE-OS 37 24 076 and 36 38 022.
The rotary pump in accordance with DE-OS 15 53 083--U.S. Pat. No. 3,303,790--has a stator with rubber-elastic vanes which perform tilting oscillating movements in accordance with the elliptical rotor. Radial pushing in an out of sealing sliding vanes is not provided. Otherwise, the construction corresponds to conventional rotary pumps. However, the medium is guided radially and axially by way of the rotor.
The pump in accordance with U.S. Pat. No. 1,963,350 has an eccentrically rotating rotor with a smooth outer wall of cylindrical shape and oscillating sealing elements which are in the shape of part cylinders in the walls of the stator and which are mounted rotatably in the stator on axially parallel spindles arranged in sealing receiving spaces of the stator which are in the shape of part cylinders. No sealing elements are fixed to the rotor. The medium is supplied and discharged axially. Curved guide faces in the interior of the rotor provide for the deflection and control of inlet and outlet. The pumping medium which emerges axially towards the lid is deflected therein and supplied by way of guide openings and apertures to the outlet at the pump stator housing. This pump, which is of technological interest from the point of view of the basic design, chooses sealing elements which are not suitable primarily for pumping media carrying sensitive constituents, such as beverages and foodstuffs which contain raw fruit such as strawberries. The many small spaces and corners can only be cleaned with difficulty. This is primarily also to be attributed to the bearings, provided with relatively small dimensions, the springs required for the sealing oscillators and the like.